What Are the Causes of Bladder Stones in Dogs?

Canine bladder stones are obstructions of the urinary tract that form from a variety of buildups. They are painful and can lead to fatal health problems if not passed. Genetics, diet and breed are all factors in their formation.

Description

Bladder stones, medically known as urinary calculi, are tiny stones that form from minerals and obstruct the kidneys, ureters, bladder and urethra. They're differentiated by their composition. Struvite stones, for instance, form from magnesium ammonium phosphate. Other stones form from calcium oxalate, calcium phosphate, cystine, ammonium urate and several more sources. Stones crystallize around a single irritant, called a nitus, which grows in size inside the urinary tract.

Symptoms

The signs of bladder stones include pain or straining while urinating, blood in the stream, and frequent urination in small quantities. Some dogs show little or no signs and the stones are only found when a vet examines the animal's abdomen during a physical examination or through abdominal X-rays. Female dogs and smaller breeds are at higher risk than male dogs and larger breeds due to their shorter urethras.

Causes

Genetics play a large role in bladder stones. Some animals' genes cause them to produce higher levels of the substances that are precursors to bladder stones. Dalmatians and English bulldogs appear to have a genetic defect that results in urate stones, a form that only results from liver shunts in other breeds. Urine pH also plays an important part in the formation of bladder stones. Struvite stones form in alkaline urine while those such as calcium oxalate stones thrive in acidic urine. Urine pH is largely influenced by diet. High amounts of magnesium, ammonium and phosphate often come from high protein diets. Bacterial infections affect urine pH and facilitate the crystallization of struvite stones. Moreover, a dog's body produces more substances that include materials for bladder stones when trying to fight off an infection.

Treatment

Treatment options for canine bladder stones depend on their size and location. About 85 percent of stones are found in the bladder itself. The gentlest method of treatment is to increase the amount of water in the dog's diet through the swapping of dry for wet food. Another method is to add more salt to the pet's diet, forcing it to consume more water. One option is urohydropulsion, a process by which the bladder is filled with saline via a catheter and is then emptied. In some cases surgical removal of the stones, called a cystotomy, is necessary. These methods are more common with calcium oxalate stones. Struvite stones can often be dissolved through dietary management recommended by a veterinarian. These diets can last as long as four months. The treatment of urate stones also involves special diets.

Considerations

The elimination or reduction of urinary tract infections is especially important in the prevention of recurring struvite stones. Bladder stones can lead to kidney shutdown and death, therefore they must be watched carefully and dealt with in a timely manner. Regular checkups are an excellent prevention strategy as well as a constant supply of clean water.

Resources

• Bladder Stone Information